Torus wedge flow meter

ABSTRACT

A flow meter for measuring the volume of fluid flowing through the meter includes an inner cylindrical tube through which the fluid flows and an outer cylindrical tube tending over the inner cylindrical tube. The outer cylindrical tube is radially spaced from the cylindrical inner tube to provide an annular cylindrical space between the inner cylindrical tube and the outer cylindrical tube. A seal between the inner cylindrical tube and the outer cylindrical tube closes the annular cylindrical space adjacent ends of the annular cylindrical space. The inner cylindrical tube further defines at least one opening in a wall of the inner cylindrical tube to balance the fluid pressure in the annular cylindrical space with the pressure in the inner cylindrical tube. A torus wedge flow restriction member is integrally formed within full internal circumference the inner cylindrical tube for restricting the flow of fluid through the inner cylindrical tube and produces a pressure drop in the fluid as it flows past the flow restriction member. The inner cylindrical tube and the outer cylindrical tube in combination further define at least one port for receiving a pressure sensing device to measure the pressure of the fluid flowing through the flow meter.

The present invention relates to flow meters in general, and inparticular to flow meters that employ a wedge-shaped flow restrictingelement producing a pressure drop within the flow meter to indicate thevolume of fluid flowing through the flow meter.

The use of wedges to create a pressure drop in flow meters formeasurement of the volume of fluid passing through a flow meter is knownin the art. Wedge-shaped flow meters are described in U.S. Pat. No.4,237,739 issued on Dec. 9, 1980, U.S. Pat. No. 4,926,698 issued on May22, 1990, and U.S. Pat. No. 6,672,173. The '739 patent describes a flowmeter using a single wedge affixed to the internal wall of the flowmeter whereas the '698 patent describes a flow meter having two opposingwedges mounted on opposite sides of the flow meter interior wall. Eitherarrangement creates an opening within the flow meter having a reducedcross-sectional area in the flow-path of the fluid thereby creating apressure differential on opposite sides of the wedge or wedges. Thepressure differential created on opposite sides of the wedges has knownmathematical relationship to the flow rate of the fluid passing therethrough, and as long as the cross-sectional area of the opening at thewedge is constant, the fluid flow measurements are very accurate. The'173 patent discloses A flow meter for measuring the volume of fluidflowing through the meter includes an inner cylindrical tube throughwhich the fluid flows and an outer cylindrical tube tending over theinner cylindrical tube. With this meter a flow restriction member ismounted to an inner surface of the inner cylindrical tube forrestricting the flow of fluid through the inner cylindrical tube andprocess a pressure drop in the fluid as it flow past the flowrestriction member.

FIG. 1 shows a typical prior art flow meter 10 shown in cross-section.Flow meter 10 generally comprises a tubular housing 12 having alongitudinal passageway 14 in which a wedge-shaped member 16 is affixedto the inner wall 18 of housing 12 thereby creating at apex 20 of wedge16 a restricted cross-sectional area represented by dimension D. Atleast two ports 22 are defined by housing 12. One of ports 22 ispositioned upstream from wedge 16 and the other ports 22 is positioneddownstream from wedge 16. Ports 22 are in fluid communication with theinterior flow through passage 14 thereby permitting the detection of thepressure differential induced by wedge 16 restricting fluid flow throughflow meter 10.

Nevertheless, fluid flow conditions under which the flow meters are usedare variable and tend to change. Specifically, temperature changes andchanges in the pressure of the fluid being measured cause the diameterof the passageway through the flow meter to expand and contract.Consequently, the cross-sectional area between the wedge apex and theflow meter wall opposite the wedge does not remain constant. Smallchanges in the flow meter passageway diameter or the distance betweenthe wedge apex and the wall opposite from the wedge can make substantialchanges in the pressure drop of the fluid flowing past the wedge.Consequently, these changes introduce unwanted errors in the calculatedvolume of fluid flowing through the meter.

Thus, there is a need within the industry for a torus 360 degreewedge-type flow meter where changes in the pressure and temperature ofthe fluid being measured by the flow meter will minimally affect theformed internal wedge element. The torus wedge is a significantdeparture from the traditional orifice plate technology and anenhancement of current wedge technology. The torus wedge flow meter willoffer a fluid profile which does not generate fluid phase separationwithin the flow stream.

SUMMARY OF THE INVENTION

One aspect of the present invention is a flow meter for measuring thevolume of fluid flowing through the meter which includes an innercylindrical tube through which the fluid flows and an outer cylindricaltube tending over the inner cylindrical tube. The outer cylindrical tubeis radially spaced from the cylindrical inner tube to provide an annularcylindrical space between the inner cylindrical tube and the outercylindrical tube. A seal between said inner cylindrical tube and theouter cylindrical tube closes the annular cylindrical space adjacent theends of the annular cylindrical space. The inner cylindrical tube allowsfluid pressure to enter the radial space between the inner cylindricaltube and the outer cylindrical tube through a surface opening oppositethe sealed end of the inner cylindrical tube to provide pressurebalancing between the pressure in the annular cylindrical space and thepressure in the inner cylindrical tube. A flow restriction member isformed within the internal circumference of the inner cylindrical tube.The flow restricted member is a torus wedge having a full internal 360degree circumference V-shaped restriction, which reduces the areaavailable to flow. Each side of the torus wedge has an inclined fluidflow surface to channel the incoming and outgoing fluid flow through thecenter annulus of the torus wedge. As fluid velocity increases due tocontraction of fluid volume at the entrance to the restriction, thekinetic energy of the fluid increases. Thus, a corresponding decrease instatic pressure or potential energy of the fluid occurs to preserveconservation of the total energy. The inner cylindrical tube and theouter cylindrical tube in combination further define at least two portsfor receiving a pressure sensing device to measure the pressure of thefluid flowing through said flow meter. In an alternative embodiment ofthe present invention, a torus 360 degree wedge member can beincorporated into the outer cylindrical tube. In this alternativeembodiment there is no inner cylindrical tube.

Another aspect of the present invention is a fluid flow meter formeasuring the volume of fluid flowing through a passageway. The meterincludes an outer housing having a first internal bore, and a removableinner member telescopically received in the first internal bore. Thefirst internal bore and an outer surface of the inner member incombination define a cannular space therebetween wherein the cannularspace is isolated from fluid flowing there through. The inner member hasa second internal bore of a first predefined cross-sectional area toaccommodate the fluid flow there through and is in pressure equalizingcommunication with the cannular space. A torus wedge metering structureis formed within the full 360 degree internal circumference of the innermember for measuring the fluid flow there through.

Yet, another aspect of the invention is a method for measuring the flowof a fluid through a tube. The method comprises the steps of providingan outer housing having an internal bore, and providing a calibratedtubular flow metering device having a torus wedge flow restrictorintegrally formed therein. The flow metering device is inserted withinthe outer housing internal bore in a telescoping fashion to create acannular space between the outer housing and the metering device. Thepressure of the cannular space is equalized with the internal pressureof the flow metering device. The combined outer housing and calibratedtubular flow metering device are coupled in the flow path of a fluid,and the pressure differential on each side of the flow restrictor isthen measured.

These and other advantages of the invention will be further understoodand appreciated by those skilled in the art by reference to thefollowing written specification, claims and appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a prior art flow meter incorporating an internal wedge torestrict the fluid flow.

FIG. 2 is a cross-sectional view, shown along a horizontal center lineof a fluid flow meter embodying the present invention.

FIG. 3 is a cross-sectional view of the circular area III of FIG. 2taken at the location where the hollow core bolt interfaces with thecalibrated tube.

FIG. 4 is a cross-sectional view of the calibrated tube taken along thehorizontal center line.

FIG. 4A is a cross-sectional view of the calibrated tube taken along thehorizontal center line, showing pressure equalization hole 90.

FIG. 5 is an alternative embodiment of a cross-sectional view of thecalibrated yube taken along the horizontal center line.

DESCRIPTION OF THE PREFERRED EMBODIMENT

For purposes of description herein, the terms “upper”, “lower”, “right”,“left”, “rear”, “front”, “vertical”, “horizontal” and derivativesthereof shall relate to the invention as oriented in FIG. 2. However, itis to be understood that the invention may assume various alternativeorientations and step sequences, unless it is expressly specified to thecontrary. It is also to be understood that the specific devices andprocesses illustrated in the attached drawings, and described in thefollowing specification are simply exemplary embodiments of theinventive concepts defined in the appended claims. Hence, specificdimensions and other physical characteristics relating to theembodiments disclosed herein are not to be considered as limiting,unless the claims expressly state otherwise.

Turning to the drawings, FIG. 2 to 4 show a flow meter 30, which is oneof the preferred embodiments of the present invention, and illustratesits various components. A preferred embodiment of flow meter 30, asshown in FIG. 2, comprises a housing 31 which receives therein an innermember 80. Inner member 80 has a central bore 82 through which a fluidflows in a direction indicated by arrow “A”. Although the fluid in FIG.2 is shown as flowing in direction “A”, this is for illustrationpurposes only, and those skilled in the art will recognize that thevarious possible embodiments permit accurate metering of fluid flowingin either direction through flow meter 30. Flow meter 30 can beinstalled in either a ‘forward’ or ‘reverse’ orientation with no effecton the accuracy or operation of the flow meter. A flow restrictor 97 isformed internally within the inner wall of inner member 80 and formspart of a metering structure. First and second port connections 47 and49 respectively are equidistantly spaced from flow restrictor 97. Firstport connection 47 is positioned upstream from flow restrictor 97 andsecond port connection 49 is positioned downstream from flow restrictor97.

As illustrated in FIG. 2, housing 31 generally comprises a tubular body32 having a flange 33 at a first end 34 thereof and a second flange 35at a second end 37. First and second flanges 33 and 35 have a pluralityof attach holes 36 to affix flow meter 30 within a pipeline. Second end37 is configured in a manner to mate with a tube or a pipe in a fluidtransmission system (not shown), and can take on a variety ofconfigurations dependent on the requirements of the fluid transmissionsystem. Housing 31 has an internal bore 42 extending longitudinallytherethrough and has a central longitudinal axis 44. Peripheral lip 43extends radially into internal bore 42 at second end 37 to define a boreopening at second end 37 that is smaller in diameter than bore 42.Peripheral lip 43 has an internal chamfer 39 which substantially facesinwardly from the opening to internal bore 42 at second end 37.

First end 34 of housing 31 has a circular recess 38 machined therein andfurther includes at least two alignment pins 40 embedded within flange33 and extending into recess 38. Alignment pins 40 are precision locatedin a predefined pattern for engagement and positioning of a first end ofinner member 80 as further described below.

Flow meter 30 has a vertical center line generally shown by dashed line45. First and second port connections 47 and 49 respectively arepositioned equidistant from centerline 45. Port connections 47 and 49,in the preferred embodiment, are connections that are commerciallyavailable and well known in the art. Port connections 47 and 49 areaffixed to tubular body 32 by welding to a top portion thereof. Each ofport connections 47 and 49 has a vertical bore 51 extending therethroughand are in fluidic communication with internal bore 42. An upper portion52 of central bore 51 in port connections 47 and 49 are internallythreaded while a lower portion 53 is a smooth non-threaded bore andgenerally of smaller diameter than upper portion 52. Each of portconnections 47 and 49 receive therein a hollow core bolt 55.

Referring also to FIG. 3, each hollow core bolt 55 has an upper threadedshank portion 59 and a lower non-threaded shank portion 61. Each bolt 55is threaded into each of port connections 47 and 49 (shown in FIG. 2) toa desired depth wherein lower non-threaded shank portion 61 extends intointernal bore 42 (shown in FIG. 2) in a sealing manner with inner member80 as further described below. Bolts 55 are retained in their verticalposition within port connections 47 and 49 by lock nuts 56 (shown inFIG. 2) engaging a portion of upper threaded shank 59 and bearingagainst a top of port connections 47 and 49. Bolts 55 also have a head58 (shown in FIG. 2) which extends above lock nuts 56. A central bore 57extends the length of bolt 55 to provide fluid communication withhousing internal bore 42. Head 58 further includes a threaded bore 60for receiving a pressure gauge or a pressure transmission tube forconnection to a pressure gauge. Smooth non-threaded shank portion 61 ofbolt 55 includes a groove 62 therearound. Groove 62 retains a firstO-ring 66 to create a pressure seal between lower smooth portion 53 ofcentral bore 51 (shown in FIG. 2) in port connections 47 and 49 andlower unthreaded shank 61 of bolt 55. Bottom 63 of bolt 55 defines asecond circular groove 64 therein which retains a second O-ring 68 forsealing engagement with inner member 80 as further described below.

FIG. 4 illustrates inner member 80 which generally comprises innercylindrical tube 81 having a flange 86 at a first end 85. Flange 86 isgenerally circular in configuration and is sized to be received withincircular recess 38 at first end 34 of housing 31 (as shown in FIG. 2).Flange 86 includes alignment pin holes 88 therein in a precision patterncoincident with the pattern of alignment pins 40 in recess 38 of housing31 (as shown in FIG. 2). Inner cylindrical tube 81 has an inner wall 83which defines an internal bore 82 extending longitudinally therethrough.Bore 82 has a central longitudinal axis illustrated by dash line 84. Asillustrated in FIG. 4A, inner cylindrical tube 81 has a pressureequalization hole 90 extending therethrough permitting fluidiccommunication between internal bore 82 and an exterior of innercylindrical tube 81. Inner member 80 has a second end 92 which has anexternal chamfer 94 at second end 37 of housing 31 (as shown in FIG. 2).Chamfer 94 is angularly oriented substantially equal to internal chamfer39 (as shown in FIG. 2) for engagement therewith. Inner member 80 has avertical center line shown by dash line 96. Vertical center line 96 ofinner member 80 and vertical center line 45 of housing 31 aresubstantially coincident when inner member 80 is received into housing31. A flow restrictor 97 is integrally formed within the inner wall 83of cylindrical tube 81. In the preferred embodiment, flow restrictor 97is a 360 degree torus wedge 98 having opposing first and second wedgemember 100 and 102 respectively. Wedge member 100 and 102 havesubstantially a full internal V-shaped circumference and are adjoined atcircular vertex 406 to form flow constrictor member 99.

Wedge member 100 and 102 each are respectively defined by circular base(400, 401) and adjoining circular vertex (406). Both base 400 and 401have a diameter coincident to the diameter of inner cylindrical tube 81.Along the circumference of base 400 and 401, internal wall 83 uniformlyinclines inwardly and converges into the circumference of vertex 406 toform constrictor member 99. The inclined V-shaped inner wall of wedgemember 100 and 102 reduces the area available to flow throughconstrictor member 99, but the inclined V-shaped inner wall alsochannels the incoming and outgoing flow through constrictor member 99.

The diameter of circular vertex 406 is smaller than diameter of base 400and 401, thereby restricting the fluid flow through internal bore 82.However, in the preferred embodiment, the diameter of circular vertex406 can be any diameter necessary to create the differential used formeasurement. Constrictor member 99 is formed within inner wall 83 ofcylindrical tube 81 such that the central radius of constrictor member99 is substantially perpendicular to both longitudinal axis 84 and thediameter of constrictor member 99 is coincident with vertical axis 96.Torus wedge 98 is retained to housing 31 by fastener 104 therebyrendering torus wedge 98 removable and readily replaceable with a toruswedge of different dimensions or configuration.

The angular inclined depth between adjoining wedge members 100 and 102as taken along vertical center line 96 perpendicular to axis 84 rangesbetween 45 and 90 degrees. Those knowledgeable in the art will alsorealize that opposing wedges 100 and 102 can also be utilized to providethe desired flow restriction with substantially the same results as asingle wedge as disclosed in the prior art. Each combined wedge 98(wedge members 100 and 102) and tube 81 can be precalibrated for use inany housing 31 without requiring recalibration of the tube-wedgecombination. However, those skilled in the art will also recognize thatthe replacement of a wedge 98 in a specific tube 81 will requirerecalibration of the wedge-tube combination.

Cylindrical tube 81 further includes circular recesses 105 at a topportion thereof. Recesses 105 are equally spaced about center line 96and upon receipt of inner member 80 within housing 31 are in verticalregistration with central bores 51 of port connections 47 and 49 (asshown in FIG. 2). Recesses 105 have a circular land 108 and a pressureport 106 extending through land 108 to internal bore 82.

FIG. 5 illustrates another aspect of the present invention wherein thetorus wedge is incorporated into outer member 380. Outer member 380which generally comprises inner cylindrical tube 381 having a flange 333at a first end 334 thereof and a second flange 335 at a second end 337.First and second flanges 333 and 335 have a plurality of attach holes336 to affix outer member 380 within a pipeline. Inner cylindrical tube381 has an inner wall 383 which defines an internal bore 382 extendinglongitudinally therethrough. Bore 382 has a central longitudinal axisillustrated by dash line 384. Outer member 380 has a vertical centerline shown by dash line 396. A flow restrictor 97′ is integrally formedwithin the inner wall 383 of cylindrical tube 381. In the preferredembodiment, flow restrictor 97′ is a 360 degree torus wedge 98′ havingopposing first and second wedge member 100′ and 102′ respectively. Wedgemember 100′ and 102′ have substantially a full internal V-shapedcircumference and are adjoined at circular vertex 406′ to form flowconstrictor member 99′.

Wedge member 100′ and 102′ each are respectively defined by circularbase (400′, 401′) and adjoining circular vertex (406′). Both base 400′and 401′ have a diameter coincident to the diameter of inner cylindricaltube 381. Along the circumference of base 400′ and 401′, internal wall383 uniformly inclines inwardly and converges into the circumference ofvertex 406′ to form constrictor member 99′. The inclined V-shaped innerwall of wedge member 100′ and 102′ reduces the area available to flowthrough constrictor member 99′, but the inclined V-shaped inner wallalso channels the incoming and outgoing flow through constrictor member99′.

The diameter of circular vertex 406′ is smaller than the diameter ofbase 400′ and 401′, thereby restricting the fluid flow through internalbore 382. Constrictor member 99′ is formed within inner wall 383 ofcylindrical tube 381 such that the central radius of constrictor member99′ is substantially perpendicular to both longitudinal axis 384 and thediameter of constrictor member 99′ is coincident with vertical axis 396.

The angular inclined depth between adjoining wedge members 100′ and 102′as taken along vertical center line 396 perpendicular to axis 384 rangesbetween 45 and 90 degrees. Those knowledgeable in the art will alsorealize that opposing wedges 100′ and 102′ can also be utilized toprovide the desired flow restriction with substantially the same resultsas a single wedge as disclosed in the prior art. In use, each combinedwedge 98′ and cylindrical tube 381 must be pre-calibrated.

In use, referring to FIGS. 1-4, a housing 31 is selected for insertionin a fluid line to measure the fluid flow therethrough. An inner member80 comprising a specific 360 degree wedge 98 and tube 81 configurationis selected based upon the type of fluid to be measured and the flowrate to be measured thereby. Inner member 80 is telescopically insertedinto first end 34 of housing 31 and aligned so that alignment pins 40 incircular recess 38 are received in alignment pin holes 88 of flange 86(as shown in FIG. 4). Engagement of pins 40 in holes 88 substantiallycenters first end 85 with respect to bore 42 (as shown in FIG. 2). Uponfull insertion chamfer 94 at second end 92 of inner member 80 isreceived by internal chamfer 39 of housing 31. The tapered surfaces ofchamfers 39 and 94 interact such to center the second end 92 of innercylindrical tube 81 within internal bore 82 of housing 31. Flange 86 ofinner member 80 is sealed against circular recess 38 and innercylindrical tube 81 is centered along its length within internal bore 42of housing 31.

Since, the outer diameter of inner cylindrical tube 81 is smaller thanbore 42, a space 110 (as shown in FIG. 3) is defined by the outerdiameter of tube 81 and inner bore 42 of housing 31 (as shown in FIG.2). Space 110 is sealed from internal bore 82 of inner member 80 exceptfor pressure equalization hole 90 (FIG. 4A) which permits the fluidpressure within space 110 to be equalized with the pressure of the fluidflowing through internal bore 82. However, because space 110 isotherwise sealed from internal bore 82, there is no fluid flowtherethrough. After inner member 80 is received and centered withininternal bore 42, hollow core bolts 55 are inserted in first and secondport connections 47 and 49. Bolts 55 are threaded down until firstO-ring 66 (as shown in FIG. 3) seals the upper portion of bore 51 fromthe fluid pressure in space 110. Further, bottom 63 of bolt 55 bearsagainst circular land 108 of inner cylindrical tube 81 such that secondO-ring 68 seals space 110 from internal bore 82. Lock nuts 56 are usedto secure bolts 55 within port connections 47 and 49 to maintain thepressure seals created by O-rings 66 and 68. Pressure gauges or fluidpressure transmission lines (not shown) can be coupled with threadedbore 60 in head 58 of bolt 55 such that when a fluid flows through bore82, the pressure differential between pressure port 106 at portconnection 47 upstream from the flow restrictor 97 can be compared withthe pressure at pressure port 106 of port connection 49 downstream fromflow restrictor 97 in a manner well known in the art to determine thefluid flow rate therethrough. The preferred embodiment permits themeasurement of fluid flow in a bi-directional manner with out loss ofmetering accuracy in either direction.

Those skilled in the art will recognize that different flow restrictorsizes, shapes and configurations can be utilized to optimize the fluidflow metering performance of meter 30, and that different quantities ofpressure sensing ports can also be utilized as alternate embodiments.Further, in addition to the foregoing description, those skilled in theart will readily appreciate that other modifications may be made to theinvention without departing from the concepts disclosed herein. Suchmodifications are to be considered as in the following claims, unlessthese claims expressly state otherwise.

1-11. (canceled)
 12. A flow meter for measuring the volume of fluidflowing through a passageway, the meter comprising: an outer housinghaving a first internal bore; a removable inner member telescopicallyreceived in the first internal bore and suspended therein, the firstinternal bore and an outer surface of the inner member in combinationdefining a space therebetween, the space isolated from fluid flowingtherethrough; the inner member having a second internal bore of a firstpredefined cross-sectional area to accommodate the flow therethrough,the internal bore in pressure equalizing communication with the space; ametering structure being formed within a wall of the inner member formeasuring the fluid flow therethrough; the outer housing has a firstflange at a first end thereof, a recess defined within the flange, andat least two alignment pins extending from a surface of the recess; andthe inner member has a second flange at a first end thereof, the secondflange abutting the first flange within the recess and further havingholes receiving the alignment pins therein for centering the innermember within the bore of the outer housing. 13-21. (canceled)
 22. Amethod for measuring the flow of a fluid through a tube, the methodcomprising the steps of: providing an outer housing having an internalbore; providing a calibrated tubular flow metering device having a flowrestrictor being formed therein; inserting the flow metering devicewithin the outer housing internal bore in a telescoping fashion tocreate a cannular space between the outer housing and the meteringdevice, equalizing the pressure of the cannular space with the internalpressure of the flow metering device; coupling the combined outerhousing and calibrated tubular flow metering device in the flow path ofa fluid; and measuring the pressure differential on each side of theflow restrictor. 23-31. (canceled)